dealer training series -...

Mobile Drivetrain FluidsA Technical Introduction to Drivetrain Lubrication | Presented by AMSOIL INC.

Dealer Training Series

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Table of ContentsMobile Drivetrain Fluids

Explana on of the Drivetrain ................................................................................................... 5Drivetrain Gear Lubricant Viscosity Grading Systems .............................................................. 5Service Types: Normal and Severe ........................................................................................... 8A ermarket ATF Addi ves ....................................................................................................... 8

Drivetrain ComponentsGears, Gear Types and the Mechanical Advantage ................................................................ 11Drivetrain Gear Types ......................................................................................................... ... 11Gear Ra os and the Mechanical Advantage .......................................................................... 12Drivetrain Components ........................................................................................................ . 15Transfer Case ................................................................................................................. ......... 16Di eren al ........................................................................................................................... .. 17Transaxles..................................................................................................................... .......... 20Power Takeo Unit ................................................................................................................. 21

Manual TransmissionsIntroduc on to Manual Transmissions .................................................................................. 25Manual Transmission Components ........................................................................................ 25Gears ......................................................................................................................... ............. 26Unsynchronized Manual Transmission Opera on ................................................................. 28Synchronized Manual Transmission Opera on ...................................................................... 28Common Manual-Transmission Lubricants ............................................................................ 30Gear Lubricants ............................................................................................................... ....... 30

Automa c TransmissionsIntroduc on to Automa c Transmissions .............................................................................. 35OEM Performance Speci ca ons for Automa c Transmissions ............................................ 35Fundamental Components of Automa c Transmissions ....................................................... 36Torque Converter .............................................................................................................. ..... 36Clutches/Clutch Packs ......................................................................................................... ... 37Planetary Gears ............................................................................................................... ....... 38Oil Pump ...................................................................................................................... .......... 39Valve Body .................................................................................................................... ......... 39Seals ......................................................................................................................... .............. 40CVT – Constant Velocity Transmissions (Con nuously Variable Transmission) ...................... 40DCT – Dual-Clutch Transmissions ........................................................................................... 41Step-Type Automa c Transmission ........................................................................................ 41

The JASO LVFA/An -Shudder Durability Test .................................................................... 42The Aluminum Beaker Oxida on Test (ABOT) .................................................................. 43Gear Durability Test .......................................................................................................... 45KRL Shear Stability Test ..................................................................................................... 46Foaming Tendency Tes ng (ASTM D-892) ........................................................................ 47

Heavy-Duty Trucks and EquipmentManual vs. Automa c Heavy-Duty Transmissions ................................................................. 51Manual Heavy-Duty Transmissions ....................................................................................... 51Fric onal Proper es ............................................................................................................... 51Automa c Heavy-Duty Transmissions ................................................................................... 52Tractor Fluids and Hydrosta c Transmissions ....................................................................... 53Powershi Transmissions ...................................................................................................... 54

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AppendixMilitary MIL-PRF-2105E Performance Speci ca ons for Lubrica ng Oil .............................. 58API Service Classi ca ons for Gear Oil .................................................................................. 59SAE J-306 Automo ve Gear Lubricant Viscosity Classi ca on............................................... 60JASO LVFA (An -Shudder Durability) Test .............................................................................. 61Aluminum Beaker Oxida on Test (ABOT)............................................................................... 62Gear Durability Test .......................................................................................................... ..... 63KRL Shear Stability Test ...................................................................................................... .... 64Brook eld Viscosity (MERCON V Limits) ................................................................................ 65Brook eld Viscosity Comparison ........................................................................................... 66Foam Sequence Tes ng ......................................................................................................... 67Foam Tendency Limits (MERCON V Speci ca on) ................................................................. 68

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Mobile Drivetrain Fluids: Drivetrain Introduction

Drivetrain Introduction: Section 1Mobile Drivetrain FluidsIntroduction

The following course is a technical introduc on to the components, opera on and lubrica on requirements of mobile drivetrain systems. Viscosity requirements for drivetrain lubricants, including industry grading systems, will be covered, in addi on to the concept of gear ra os, major drivetrain components, common addi ves in drivetrain lubricants and the importance of controlled fric onal proper es for these uids.

Upon comple on of this course you will have a basic understanding of the opera on and uid requirements of mobile drivetrain equipment.

Section Objectives

A er studying Sec on 1, you should understand and be able to explain the following terms and concepts:

1. Components that make up a vehicle’s drivetrain2. The drivetrain’s primary func on in the vehicle3. Current changes being made to drivetrain systems and the reasons

behind them4. Condi ons that create severe service vehicle opera ng condi ons5. Addi ve supplements6. Key tools for selling AMSOIL products and drivetrain uids

Section Keywords

The following keywords are de ned in this sec on. Pay par cular a en on to their explana ons as these concepts will serve as building blocks for future lessons.

DrivetrainTorqueTransaxle

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Explanation of the Drivetrain The drivetrain consists of all the components, located between a vehicle’s engine and wheels, that allow a vehicle to move. The drivetrain’s job is to generate the necessary thrust and rota onal force, referred to as torque, to keep a vehicle moving despite changing opera ng condi ons.

The transmission uses the rota on of the engine’s cranksha to increase and decrease torque by genera ng di erent gear ra os. The transmission makes torque adjustments based on driving condi ons such as speed changes, load, inclines and cornering. For example, if loading condi ons for the vehicle increase (i.e. traveling uphill), the transmission increases the torque output to prevent the vehicle from slowing down; this is accomplished as the transmission downshi s into a lower, more forceful gear.

Transmissions that are located in close proximity to the driven axle are o en combined with the axle components and is collec vely referred to as a transaxle. Transaxles are most common in front-wheel-drive (FWD) vehicles.

The drivetrain system encompasses other components such as the di eren al, transfer case and power-takeo unit. Each of these parts ful lls a di erent func on within the drivetrain system. These components will be discussed in greater detail later in the course.

Drivetrain Gear Lubricant Viscosity Grading Systems

Viscosity is the most important property when selec ng a gear lubricant. Industry organiza ons have created di erent grading systems to simplify lubricant selec on for gear oils. The three most common gear lubricant grading systems are developed and maintained by the American Petroleum Ins tute (API), the Society of Automo ve Engineers (SAE) and the U.S. Military.

Explanation of the Drivetrain

Drivetrain Fluid Functions

Figure 1.1The drivetrain is all of the components between the engine and wheels that propel a vehicle in motion.

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Figure 1.2American Petroleum Institute service classi cations for gear oil

Figure 1.3Society of Automotive Engineers gear lubricant viscosity classi cation (SAE J-306)Reprinted with permission from SAEJ306 ©2005 SAE International.

Drivetrain Gear Lubricant Viscosity Grading Systems

The API classi es gears using GL ra ngs, ranging from GL-1 to GL-5 (Figure 1.2). Higher GL ra ng numbers represent more severe applica ons; GL-1 is the least severe and can usually be sa s ed with a motor oil, while GL-5 is the most severe GL ra ng. Gear lubes mee ng the MT-1 ra ng must be non-reac ve with the copper and copper alloys o en used in fric on surfaces in manual transmissions. See pages 28 - 29 for more informa on on manual transmission synchronizer elements.

Gear lubricants are o en referred to as grease; however, this is technically incorrect because gear lubricants more closely resemble motor oils than grease. Another common misconcep on is that gear lubricants are thicker than motor oil, which is usually untrue.

SAE gear lubricant grade numbers are larger than SAE motor oil grades; however, this does not mean they are necessarily thicker than motor oils. Gear lubricant grades are determined on a di erent grading scale than motor oils. Rather than use the same classi ca on guidelines, two separate grading systems were developed to minimize confusion between SAE gear oil and motor oil grades.

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Figure 1.4The military drivetrain gear lubricants grading system (MIL-PRF-2105E)

The SAE J306 classi es gear lubricant viscosity grades (Figure 1.3). See the Viscosity Comparison chart for comparisons of SAE motor oil and gear oil grades (Figure 1.5).

Figure 1.5Comparison of the various viscosity grading systems. SAE gear oils of similar viscosity to SAE engine oils have a higher grade number.

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Service Types: Normal and Severe

Transmission uid change intervals are based on the service duty of the transmission; however, the de ni ons for normal and severe service vary by manufacturer.

Service de ni ons can be found in owner’s and service manuals and should be referred to when determining the proper drain interval and uid requirements for the transmission. AMSOIL-recommended product

intervals are outlined in the Product Recommenda on and Drain Interval Chart (G1490) or in the relevant AMSOIL product data bulle n.

Refer to www.amsoil.com for details.

Aftermarket ATF Additives

Unlike the oil industry, which is regulated by the API, there is no board to oversee a ermarket addi ves. This should be taken into considera on when purchasing or adding unknown chemistry to vehicles.

AMSOIL drivetrain uids and gear lubricants have precisely balanced addi ve chemistries that can be nega vely a ected by adding a ermarket addi ves. A ermarket addi ve chemicals can shorten the life of the lubricant and can result in costly damage to the drivetrain.

While a ermarket transmission uid addi ves may provide short-term bene ts, they typically cause harmful chemical imbalances that result in increased wear and corrosion to the drivetrain. Some a ermarket addi ves have been shown to increase the cold-temperature viscosity of transmission uids, impairing uid ow in the transmission during cold starts.

Figure 1.6Common OEM severe service operating conditions include frequent towing, hilly/mountainous driving, eet service and dusty and dirty environments.

Service Types: Normal and Severe

Aftermarket ATF Additives

ATF Markets and How to Sell

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Section Review1. What is the primary func on of a vehicle’s drivetrain?

__________________________________________________________

__________________________________________________________

2. A ermarket addi ves can change the viscosity of a drivetrain uid.

True or False

3. Describe a business opportunity in your hometown for selling a drivetrain uid.__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

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Mobile Drivetrain Fluids: Drivetrain Components

Mobile Drivetrain Fluids: Section 2Drivetrain ComponentsIntroduction

Sec on 2 details the use of gears and gear lubricants in automo ve systems, the major components of the drivetrain system and basic opera on and lubrica on requirements.

This sec on ends with a technical introduc on to transaxles.

Section Objectives


1. Five primary func ons of gears in a mechanical system2. Concept of ‘torque’3. Principle of gear ra os4. Role of the transmission in a vehicle’s drivetrain5. Func on of the transfer case and where it’s found 6. Understanding of the open, limited-slip and locking di eren al7. Func on of a transaxle unit

Section Keywords


Di eren alGear Mul plica onGear Ra oGear Reduc onLimited-Slip Di eren alLocking Di eren alOpen Di eren alPower-Takeo TorqueTorque Mul plica onTorque Reduc onTransaxleTransfer Case

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Gears, Gear Types and the Mechanical Advantage

Gears are found in many useful devices such as motorized tools, meters, electronics, clocks, cars and trucks. Gears’ key advantage is their ability to transfer energy in a consistent manner and increase and decrease that energy as needed.

Drivetrain gear set design varies. Di erent gear styles and orienta ons are used depending on the need for rota onal speed, degree of gear reduc on, torque loading and direc onal change. An understanding of the gears and forces involved in their opera on will provide a be er understanding of the lubricants necessary to ensure proper opera on and durability.

Simply put, gears are valuable because they accomplish one or more of the ve primary func ons of mechanical rota on:

1. Reverse direc ons2. Change speeds3. Transfer to a di erent axis4. Synchronize between separate axes5. Mul ply or reduce torque

All of these func ons occur in the drivetrain system by a variety of gear types.

Torque, the force required to rotate an object, is produced in the drivetrain on a near-constant basis. A uid barrier is used to help drivetrain components withstand this torque. The uid must also absorb, reduce and disperse the energy. Without a uid barrier to dissipate the energy, gears and other mechanical components would inevitably break down a er minimal use. It is the lubricant that gives these mechanical components las ng power.

Drivetrain Gear Types

All gear types require lubrica on to protect them from fric on and wear. Yet, there are certain gear styles that have greater wear protec on and extreme-pressure (EP) protec on requirements than others. The following is not a complete list of all gear types, but explains the most common gears found in drivetrain assemblies.

Spur (Straight cut)Spur gears are widely used in parallel sha applica ons due to their low cost and high e ciency. Spur gears transmit

minimal sliding ac on as they mesh with each other, so they are usually used in low-speed applica ons. Only one pair of teeth makes contact at a given me, which limits the load capacity of the spur gear.

Limita ons of the spur gear include excessive noise and backlash during high-speed opera on.

Gears, Gear Types and the Mechanical Advantage

Drivetrain Gear Types

HelicalHelical gears have teeth that are cut at an angle toward the gear face. Contact between the teeth of helical gears is gradual; the teeth begin to make contact at one end and touch the other end as the gear rotates. Because the helical gear teeth engage gradually, they operate more quietly and have a higher load capacity than spur gears. Helical gears are used in manual transmissions to transmit power to parallel sha s.

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Spiral BevelSpiral bevel gears have curved, oblique teeth that are cut in a spiral con gura on. Spiral bevel gears are used to transmit power between

perpendicular (90°) sha s. The spiral con gura on of the gear teeth allows more teeth to make contact during mesh and

greatly increases the gear’s load capacity. When used in a di eren al, spiral bevel gears are referred to as hypoid gears.

When spiral bevel gears mesh, the teeth make sliding contact against each other, which typically

requires extreme-pressure for ca on to provide su cient wear and loading protec on because most of the lubricant is wiped away.

Gear Ratios and the Mechanical Advantage

Planetary (Combination of Spur Gears)Planetary gear sets feature a specialized type of gear arrangement consis ng of a large outer gear with a number of smaller, meshed gears nested inside of it. Planetary gears are an important component of automa c transmissions and provide gear ra o changes to accommodate driving condi ons.

Di erent gear combina ons engage to achieve the desired torque, speed and direc onal output. Bands are used to engage and disengage the gears so they do not have to physically disconnect from each other. The bands lock and unlock the planetary gears so they can either be part of the gear train, or held sta onary.

Gear Ratios and the Mechanical Advantage

A gear ra o is the rela onship between the number of teeth of two mated gears. It measures the number of rota ons a gear makes rela ve to its mated gear. For instance, Figure 2.1 shows two mated gears with a 1:1 gear ra o. These gears have the same number of teeth and will therefore rotate at the same speed. The ra o 1:1 implies that for every complete rota on the drive gear makes, the driven gear also makes one complete rota on.Di erent size gears are mated together to change speed and torque output.

Figure 2.11:1 gear ratio

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Figure 2.2 shows a 1:2 gear ra o. The drive gear is twice the size of the driven gear. For every rota on the drive gear makes, the driven gear rotates twice. A 1:2 gear ra o describes a gear mul plica on/torque reduc on because the output speed is faster and the load capacity is reduced.

Figure 2.3 shows a 2:1 gear ra o. The drive gear is half the size of the driven gear. A 2:1 gear ra o describes a gear reduc on/torque mul plica on because the output speed is slower and load capacity is increased.

Simply stated, the driven gear is capable of moving two mes the load compared to the drive gear, which is a direct result of the gear ra o between the two mated gears.

The mechanical advantage of mul -ra o gear trains allows speed and load outputs to be tailored as gears of di erent sizes are mated together.

Figure 2.32:1 gear ratio, gear reduction/torque multiplication

Figure 2.21:2 gear ratio, gear multiplication/torque reduction

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Figure 2.4 illustrates the concept of gear ra os and how they a ect the torque output of a transmission. The gears on the le represent the drive gear, while the gears on the right are being driven.

Gears 1 - 3 are low gear ra os where gear reduc on/torque mul plica on occurs. The lower the gear, the easier it is for the engine to produce power and move the vehicle from a stands ll; however, while lower gears produce more power, they restrict how fast the vehicle can travel.

In fourth gear, speed and power reach equilibrium. Fi h gear represents gear reduc on/torque mul plica on. While the power output of h gear is lower than rst gear, it allows the vehicle to travel at a much faster speed.

Figure 2.4Gear ratios and torque output as they relate to a vehicle’s transmission (illustrative purposes only)

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Drivetrain Components

This por on of sec on 2 describes why vehicles need a transmission and outlines the bene ts they provide for energy e ciency and fuel use.

Why is the Transmission Necessary?Transmissions transfer the engine’s power to the wheels and provide the ability to increase and decrease that power – torque mul plica on or torque reduc on – and can do so at varying speeds.

Changing gears from rst to third is an example of torque mul plica on where the power output of the transmission decreases, but the speed output increases.

Energy Transfer from Engine to Wheels: Synchronize Rotation SpeedIn order to understand the true need for the transmission, it is important to rst discuss an inherent limita on of the internal combus on engine. Internal combus on engines operate within a par cular range of revolu ons per minute (rpm).

Internal combus on engines are capable of a rela vely wide range of rpm, generally 600 – 7,000. On the other hand, the wheels have a limited rota onal speed, generally 0 – 1,800 rpm.

The transmission can reconcile these inherent speed limita ons, allowing the wheels to increase to an

op mal driving speed while allowing the engine to operate at an e cient rpm. In other words, the

transmission lets the wheels rotate as fast as the driver wants while allowing the engine to rotate

at a speed that maximizes fuel use.

As driving condi ons change, the torque and speed required by the wheels di er. Changing gears allows the engine to maximize the

amount of work it is doing while using fuel e ciently.

Newer vehicles are being engineered with six, seven and eight available gear ra os. These addi onal gear ra os provide maximized engine e ciency over a wider range of speeds.

Both automa c and manual transmissions are designed to achieve maximized fuel e ciency for various driving condi ons. The manner in which this is achieved varies to some extent. Sec ons 3 and 4 cover the di erences between manual and automa c transmissions in detail.

Drivetrain Components

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Transfer Case

The transfer case is used in four-wheel drive (4WD) systems to divide the torque output of the transmission to the front and rear axles. Transfer cases are also installed in all-wheel drive (AWD) vehicles and are typically a ached to the rear of the transmission.

The transfer case is able to divide transmission torque by using gears or chains to power output sha s that connect the vehicle’s front and rear drive axles. The AWD/4WD condi on is achieved when both front and rear axles are engaged.

A transfer case can be gear driven or chain driven. Gear driven designs are more durable and are usually used on large truck applica ons. Chain driven transfer cases are lighter and operate more quietly; they are usually installed on compact and full-size trucks and SUVs.

Automatic Transfer Case Operation Transfer cases can be operated with a selector lever or electronicallycontrolled push bu on. Both styles allow the operator to choose between 2WD and 4WD modes. Some transfer cases allow the operator to select di erent gear ra os, typically high and low.

Full- me transfer case units remain in 4WD un l the vehicle reaches a predetermined cruising speed, at which point they change to 2WD for safer handling. For instance, the New Process 203 transfer case unit remains in 4WD un l about 30 mph. Generally, 4WD vehicles transfer power only to the rear axle during normal opera on, and the front axle is engaged during the 4WD mode.

Vehicles with a 2WD/4WD selector lever operate di erently from those equipped with a full- me transfer case unit. In two-wheel-high (2H) mode, only the rear axle is driven. During the four-wheel-high (4H) mode, the transfer case divides torque to both the front and rear drive axles and allows the axles to rotate at di erent speeds.

In the 2L/4L (low gear mode), the transfer case engages a second set of reduc on gears that locks the axles together so they rotate at the same speed. This condi on, while not op mal for high-speed driving, is well-suited for o -road condi ons where steep grades and uneven terrains are maneuvered.

Manual Transfer Case OperationThe ability to change drive mode (e.g. from 4H to 2H) varies depending on transfer case design. The internal components of the transfer case responsible for changing drive mode dictate most of the uid property requirements for the unit.

For a 4WD vehicle with a manual transfer case, engaging and disengaging the front axle requires the vehicle to decelerate. Many newer truck manufacturers advise shi ing the transfer case gears below speeds of 3 mph.

Automa c transfer case units are most common on newer vehicles and can be operated at faster speeds. They are electronically actuated and use clutches to transfer rota on to the drive sha .

Transfer Case

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Lubricant RequirementsThe gears and chains of the transfer case endure a majority of the stress during extreme opera on and o -road condi ons such as snow plowing or rock climbing.

Shi -on-the- y automa c transfer case units can shi between 2WD and 4WD while moving. The shi -on-the- y transfer case uses a synchromesh unit that has speci c addi ve requirements for fric on and copper corrosion protec on.

Refer to owner and service manuals for transfer unit speci ca on requirements. AMSOIL formulates a number of lubricants that meet most applica on requirements. The AMSOIL Online Lookup Guide can be used to determine uid equivalents that meet or exceed speci ca ons for most applica ons.

Diff erential

The di eren al divides rota on from the drive sha to the two sides of a vehicle’s drive axle in order to turn the wheels. Di erent di eren al designs handle the division of torque di erently, and these di erences a ect vehicle handling in certain condi ons.

The open di eren al allows the wheels on opposite sides of the axle to turn at di erent speeds, or slip. By allowing the

opposite sides of the drive axle to slip, vehicle handling during cornering is improved.

While making turns, the vehicle’s outer wheel travels a farther distance than the inner wheel. If the axle were locked so both wheels were forced to turn at the same speed, the outer wheel would drag and hop along the ground because it would not be able to rotate fast enough. This would put excessive wear on the outer wheel and its components and create unpredictable and unsafe driving condi ons.

Because open di eren als transfer torque to the wheel o ering the least amount of resistance, they cannot transfer torque to the opposite wheel in low-trac on scenarios, such as a wheel losing trac on on a piece of ice. This restric on of torque transfer prevents the vehicle from moving.

Differential

Figure 2.5Open differential

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The limited-slip di eren al was developed to overcome this limita on; it is designed to transfer torque to the opposite wheel in low-trac on scenarios.

Limited-slip di eren als operate in a similar manner to open di eren als by allowing the wheels on opposite ends of the drive axle to rotate at di erent speeds during cornering. However, in low-trac on scenarios, the limited-slip di eren al transfers torque from the wheel o ering the least resistance to the opposite wheel. It is designed to provide the wheel with enough trac on to move the vehicle. If a wheel loses trac on and slips, a spring pack and set of clutch packs are used to lock and engage the opposite side of the drive axle so that the opposite wheel rotates.

A locking di eren al permanently locks the two sides of the drive axle together and does not allow them to slip at all. Locking di eren als produce extra wear on the drivetrain and res during cornering and are not used in street applica ons for this reason.

O -road applica ons o en use locking di eren als because driving surfaces are typically so and in ict li le damage to res during cornering.

Extreme Pressure The opera ng environment within the di eren al is extremely harsh. High temperatures are produced as the gears interact, and high levels of pressure strain gears and bearings. To protect the di eren al in these extreme condi ons, lubricants are engineered to have speci c characteris cs that resist thinning, provide extreme-pressure protec on and resist the e ects of oxida on.

The meshing gear teeth cause much of the lubricant to be wiped o tooth surfaces. EP addi ves bond to the surface of the gear teeth to protect them from the pressure. AMSOIL lubricants reduce fric on and wear and help prolong component life by providing EP protec on with an iron-sul de barrier.

Extreme Temperature and Thermal Degradation ResistanceModern vehicles designed for aerodynamics, coupled with larger cabin sizes, restrict the air ow to the di eren al and cause it to operate at increased temperatures. The increased size and horsepower of modern vehicles subject the di eren al to high loads that also increase the amount of heat generated inside the unit.

Lubrica ng uid for the di eren al is responsible for adequately cooling the components; however, newer di eren al sump designs hold less lubrica ng uid than previous models. Lubricants used in these newer applica ons have to perform against these added challenges, and they must do so with less volume.

AMSOIL synthe c lubricants are ideal for these hot environments because of their inherent resistance to high temperatures. The uniform composi on provides stability under extreme heat and resists thermal breakdown to maintain an impervious uid barrier between components.

Figure 2.6Limited-slip differential

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RustDi eren al housing designs incorporate air vents to accommodate

pressure changes as air temperatures uctuate. When warm air is drawn into the cool di eren al housing,

condensa on forms on surfaces and encourages rust and corrosion.

In addi on to ea ng away metal surfaces, rust and corrosion shed abrasive par cles that damage the inner workings of the gear system. These harmful

par cles cause minute pi ng and scoring as the gears mesh, which eventually results in gear failure.

AMSOIL uids are treated with a robust rust-inhibitor package that combats rust development in the drivetrain

system.

FoamingFoaming poses a serious threat to the di eren al by introducing excessive amounts of compressible air into the uid. It can be caused by over- or under- lling the sump and incompa ble base oils or addi ve packages. In addi on to compromising the lubricant barrier and permi ng increased fric on between components, foam increases opera ng temperatures by ac ng as a heat insulator.

AMSOIL transmission uids help prevent the forma on of foam with defoamants that reduce the surface tension of bubbles. This ensures that any foam development will rapidly dissipate to prevent excessive fric on and heat reten on.

FrictionLimited-slip di eren als require controlled fric onal proper es for responsive clutch engagement and disengagement. Fric on modi ers reduce the poten al for clutch cha er that damages clutch plate surfaces. Cha er is the uninten onal s ck-slip engagement of the clutches and is caused by a lack of proper fric on modi ers in the lubricant.

AMSOIL lubricants are fully for ed with controlled fric on modi ers to maximize fric on surface performance. Fric on modi ers allow clutch plates to engage and disengage properly and ensure smooth and safe di eren al opera on.

Transaxles

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Transaxles

The transaxle is a compact component that combines the transmission, di eren al and associated components of the driven axle into one integrated assembly. Transaxles are typically used in applica ons where the engine and the drive axle are on the same end of the vehicle, such as in front-wheel-drive cars. Typically, gears in the transaxle are spiral bevel, spur or helical.

When the engine, transmission and di eren al are separate units, a number of direc onal changes are required to transfer torque through the drivetrain assembly. When these components are separate, the engine is perpendicular to the driven axle, requiring a 90-degree turn. Figure 2.7 illustrates the power ow in a vehicle where engine, transmission and di eren al are separate components. No ce how the direc on of torque from the drivesha to the nal-drive axle requires a 90-degree turn. A perpendicular change in rota on generally requires the use of hypoid gears that require a heavy-duty, EP-for ed lubricant.

In most cases, transaxles eliminate the 90-degree direc onal change because the engine, transmission and di eren al are oriented in-line with the nal drive axle, not perpendicular to it. Figure 2.8 illustrates the direc on of energy transfer from the transaxle to the nal drive axle. No ce how the direc on of energy transfer is in-line from the transaxle

Figure 2.7Rear-wheel drive con gurations typically accomplish a 90° turn in the differential by using hypoid gears, which require an EP-forti ed uid.

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to the nal drive axle. Because the energy transfer is in-line, helical gears can be used to power the drive axle. Helical gears have less demanding requirements for wear and EP protec on than hypoid gears, and can o en be adequately lubricated by an automa c transmission uid (ATF).

LubricationLubricant performance must provide protec on for both the transmission and synchronizer elements of automa c transaxle units, making API GL-4 and GL-5 gear lubes unsuitable due to their EP addi ve content. Typically, FWD automa c transaxles can use an automa c transmission uid. AMSOIL o ers two automa c transmission uids formulated to exceed manufacturers’ speci ca ons: Mul -Vehicle Automa c Transmission Fluid (ATF) and Synthe c Fuel E cient Automa c Transmission Fluid (ATL).

Manual transaxles o en require a transmission uid that meets gear lubricant speci ca ons. For example, some manual transaxles specify an API Service GL-4, GL-5 or MTF uid.

Refer to owner and service manuals to determine speci c lubrica on requirements. The AMSOIL Online Lookup Guide is a tool to cross-reference appropriate uids that meet and exceed speci ca ons in most applica ons.

Power Takeoff Unit

More commonly referred to as a PTO, the power takeo assembly is used to power an accessory unit that has nothing to do with moving the vehicle. Power takeo units are generally found on larger, heavy-duty equipment like refuse haulers and farming equipment.

PTOs use gears that are mated directly to the transmission to convert its energy to power the accessory unit. Some examples include a PTO-driven winching system, a l ng bed

Figure 2.8The transaxle eliminates the need for an EP-forti ed uid because the engine and transmission are in-line with the drive axle, using helical gears that do not have EP requirements.

Power Takeoff

Figure 2.9A power takeoff unit attached to a large vehicleImage used with kind permission from “Factory Direct” a division of “Seneca Tank.”

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on a dump truck, water pumps on re trucks or garbage compactors on refuse haulers. PTO units are most o en used to power hydraulic systems.

PTO units in manual vehicles are typically mounted to the vehicle’s transmission and are driven by a counter sha or reverse idler gear. In automa c transmissions, the unit is o en driven before the torque converter.

PTO units do not have a dedicated lubricant sump and use the transmission’s uid source for lubrica on.

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Section Review1. Name three of the ve primary func ons of gears in a mechanical

system.__________________________________________________________

__________________________________________________________

2. To achieve torque mul plica on, the drive gear would be larger than the driven gear. True or False

3. To achieve a torque reduc on, the drive gear would have to be _______________ than the driven gear

4. List the two func ons of the transmission. __________________________________________________________

__________________________________________________________

5. What is the purpose of a transfer case?__________________________________________________________

__________________________________________________________

6. Describe the limita on of the open di eren al when one of the drive wheels has no trac on. __________________________________________________________

__________________________________________________________

7. How does the limited-slip di eren al overcome the problem described in Review Ques on #6? __________________________________________________________

__________________________________________________________

8. In what applica ons would a locking di eren al be necessary? __________________________________________________________

__________________________________________________________

9. Why can rust forma on jeopardize gear integrity? __________________________________________________________

__________________________________________________________

10. Why are EP-for ed lubricants generally not used in transaxle applica ons? __________________________________________________________

__________________________________________________________

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Mobile Drivetrain Fluids: Manual Transmissions and Transaxles

Mobile Drivetrain Fluids: Section 3Manual TransmissionsIntroduction

Sec on 3 begins with a descrip on of the components and opera on of manual transmissions. Manual transmission components that rely on manual transmission uid (MTF) for proper opera on are discussed, with an emphasis on uid requirements and addi ve considera ons.

Section Objectives


1. Func on of the manual transmission2. Di erence between a manual transmission and automa c transmission3. Di erence between the constant-mesh manual transmission and the

sliding-gear manual transmission4. The func on of the synchromesh unit in the manual transmission and

its lubrica on requirements

Section Keywords


ClutchSliding-Gear Manual TransmissionSplineSynchromesh Unit Synchronized Manual Transmission

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Introduction to Manual Transmissions

The manual transmission transfers engine power to the vehicle’s nal drive components. It is characterized by a driver-operated clutch that physically links the engine and transmission.

This sec on focuses on the general opera on of the manual transmission and the importance of proper lubrica on and controlled fric onal proper es.

Manual Transmission Components

The sliding-gear manual transmission consists of unsynchronized gears in the gearbox. Although the sliding-gear manual transmission is no longer used in modern vehicles, a basic understanding of its opera on serves as the founda on for understanding the opera on and lubrica on requirements for the modern synchronized manual transmission.

Major components of the manual transmission are iden ed below. Refer to Figure 3.1 on the following page for a visual representa on.

ClutchThe clutch physically links the engine to the transmission and is controlled by the operator via the clutch pedal. The engaged clutch transfers rota on from the engine’s cranksha to the transmission’s laysha so that they rotate at the same speed.

Layshaft/Cluster GearThe laysha is a solid component that holds a gear mate for each drive gear on the output sha . This en re unit is o en referred to as the “cluster gear.”

Output ShaftThe output sha holds all of the drive gears, dog gears and synchromesh units. It transfers rota on to the drivesha .

Drive gearsHelical drive gears are located on the output sha ; they ride on bearings that allow them to spin freely on the output sha . Each gear contains a spline and teeth used to lock the drive gear to a dog gear. A spline is a mechanical key that is a ached to one of two connected parts.

Synchromesh (Not included in sliding-gear manual transmissions)The synchromesh unit (Figure 3.2) is a conical, bronze ring a ached to each drive gear. It’s fric on surface matches the speed of rota on between the drive gear and dog gear to provide smooth gear ini a on.

Dog Gear (Not included in sliding-gear manual transmissions)Some mes referred to as the dog collar, the dog gear contains teeth that lock the selected drive gear to the output sha .

Selector ForkThe selector fork moves the dog collar to the selected drive gear, it is controlled by the operator via the gear selector lever.

Introduction to Manual Transmissions

Manual Transmission Components

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Figure 3.1Manual transmission components

Figure 3.2Synchromesh unit

Gears

Helical gears are usually used in manual transmissions because of their quiet opera on and high load capacity. The helix pa ern of the teeth provides superior tooth strength that makes them ideal for manual transmission applica ons.

The lubrica ng uid minimizes gear wear and heat buildup to improve gear e ciency and inhibit the corrosion of gear surfaces. A high-quality lubricant is cri cal for op mal protec on and performance because the rela ve mo on between the gears squeezes out the oil between gear teeth.

Straight motor oil or automa c transmission uids typically provide enough protec on for most manual transmission parallel sha applica ons.

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GL-4 lubricants may be speci ed for applica ons that require an -wear and mild-EP addi ve content. GL-5 lubricants may be speci ed for applica ons that require high EP content.

Clutch The clutch physically links the engine to the transmission and controls the transfer of power between the components. It is connected and disconnected from the engine via an operator-controlled clutch pedal that allows the drives to change gears while the vehicle is moving. When the clutch is disengaged, the engine can remain running while the vehicle is stopped. When the clutch is engaged, a solid physical connec on between the engine and transmission is achieved by the clutch’s fric on materials.

OperationClutch components work together to control engagement and disengagement of the clutch plate to the engine’s ywheel.

The ywheel is located to the rear of the engine and is a ached to the cranksha . The ywheel helps absorb shock impulses and provides momentum.

The clutch plates are located between the ywheel and the pressure plate; they create the physical link between the engine and transmission when the clutch is engaged. The pressure plate is bolted to the ywheel and rotates at engine speed. When the clutch is engaged, the pressure plate pushes the clutch plates against the ywheel to create a solid connec on.

The surface of the ywheel is machined to have fric onal characteris cs so that it will mate with the clutch plate properly and prevent slipping.

Gears

Figure 3.3Typical manual transmission clutch assembly

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Unsynchronized Manual Transmission Operation

Sequence of a Gear Change in an Unsynchronized Manual Transmission1. While the vehicle is moving, a single drive gear is mated with the

selected gear on the laysha .

2. During a gear change, the selector fork moves the drive gear to the desired laysha gear.

3. The driver must manipulate engine rpm speed so that its matches the speed of the laysha . Engine speed can be reduced and the transmission can move into a lower gear, or engine speed can be increased by opening the thro le (stepping on the gas pedal) and the transmission can move into a higher gear. The sliding gear mates with the various sized laysha gears to achieve di erent gear ra os.

Synchronized Manual Transmission Operation

Sequence of a Gear Change in a Synchronized Manual Transmission 1. While the vehicle is moving, the selected drive gear is locked to the

output sha by the dog gear. All other gears are spinning freely on the output sha at engine speed.

2. During a gear change, the selector fork moves the dog gear to the selected, free-spinning gear.

3. The inner surface of the dog collar makes contact with the synchromesh unit xed to the drive gear. Fric on between the dog gear and synchromesh material force the drive gear and output sha to match speeds while simultaneously locking the drive gear to the output sha .

The illustra on to the le shows a synchronized manual transmission. No ce how gears 1 – 5 on the output sha are mated to a gear on the laysha . In an unsynchronized sliding-gear manual transmission, only one gear would ride on the output sha , and it would have to slide into place to mate with the operator-selected gear on the laysha .

The synchronized manual transmission is

characterized by mul ple drive gears on the output sha . In contrast, the sliding-gear manual transmission has a single drive gear on the output sha that must physically slide into posi on.

Just as some nesse is required to match gear speeds in a sliding-gear manual transmission, the dog gear and drive gear on the output sha must also match speeds to ensure the gear change is smooth as they lock together. The synchromesh unit is used to accomplish this task.

Unsynchronized Manual Transmission Operation

Figure 3.4Layout and typical components of a synchronized manual transmission

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The synchromesh unit – o en referred to as the synchro, synchronizer or synchromesh gear – is a key element to the synchronized manual transmission and is responsible for matching the speeds between the free-spinning drive gear and the output sha . Without the synchromesh unit, the gears spinning at di erent speeds would clash as they try to mate.

Synchromesh OperationWhen the selector fork moves the dog gear to the selected drive gear, the inner surface of the dog gear makes contact with the synchromesh unit. The fric on between the two surfaces causes the components to match speeds and allows the gears to mate without clashing. As the speeds of the components synchronize, the dog gear locks the selected drive gear to the output sha , causing the output sha to rotate at engine speed. The en re process happens rela vely quickly and in correctly opera ng transmissions, goes unno ced.

If the gears are shi ed too quickly, a grinding noise can be heard; however, it is not gears that are grinding. Quick shi s prevent the synchromesh unit and dog gear from completely synchronizing speeds, so the dog gear’s teeth clash with the drive gear’s dog teeth.

Synchromesh LubricationProperly engineered lubricants are required for the synchromesh unit to operate properly. Lubricant viscosity and fric on proper es are extremely important for the proper opera on of the synchronizer unit. Viscosity that is too high could prolong the gear-shi process and increase fric on and heat inside the component. Viscosity that is too low could cause the synchronizer and dog gear to move into place too quickly. The uid’s fric onal proper es must be precisely engineered. If the lubricant is engineered to be too slippery, it can prolong synchromesh transfer and cause the fric on material to wear down prematurely.

Typically, the lubricant cannot contain high levels of an -wear and EP addi ves because they will deteriorate synchromesh materials and disrupt gear engagement.

Synchronized Manual Transmission Operation

Figure 3.5Synchromesh unit

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Common Manual Transmission Lubricants

Requirements & Product Specifi cationsModern manual transmissions have speci c requirements for lubricant and addi ve proper es. Therefore, selec ng the appropriate grade of lubricant with the proper addi ve package is extremely important when replacing the transmission’s uid.

Manual transmissions may call for a motor oil, an ATF, a GL-4 or GL-5 uid, or MTF synchromesh uid. Motor oils are common manual transmission lubricants in older vehicles, but they generally do not o er adequate protec on in modern transmissions. When servicing modern vehicles, an ATF, GL-4 or GL-5 gear lubricant, MTF synchromesh or specialty transmission uid will most likely be required.

Refer to the API Automo ve Service Classi ca ons for Gear Oil Chart on page 6 (Figure 1.2) for a detailed explana on of these lubricant classi ca ons.

When replacing the uid in a manual transmission it is important to use a uid that is recommended for the original equipment manufacturer (OEM) uid speci ca ons, including viscosity grade and addi ve package.

OEM FluidsOEMs o en specify their own branded uid for service- ll use. These uids are engineered to meet par cular viscosity and fric onal performance that support the components and materials incorporated in the transmission. AMSOIL formulates uids that go beyond OEM performance speci ca ons, providing maximized performance and protec on for equipment.

ATFAutoma c transmission uid is increasingly being speci ed for manual transmissions because it provides improved shi quali es at low temperatures. The low viscosity of ATF provides fuel e ciency gains over typical gear lubricants. The addi ve package in typical ATF provides the necessary an -wear, oxida on and corrosion protec on required of the manual gearbox; however, older manual transmissions usually require a higher-viscosity uid.

Synchromesh FluidsSynchromesh uids are engineered for controlled fric onal proper es. These specialized formula ons facilitate proper synchromesh engagement and provide the correct balance of lubricity and fric on to enhance the manual transmission’s service life.

OEMs formulate these specialty uids for certain transmission models. For instance, the GM Synchromesh Transmission Fluid is a mineral-based lubricant speci ed for Tremec and New Venture Transmissions because it has been for ed with special fric on modi ers. AMSOIL Manual Synchromesh Transmission Fluid (MTF) is suitable for this and most GM synchromesh applica ons. Refer to the applicable AMSOIL data sheet or the AMSOIL website for speci c and up-to-date informa on on product speci ca ons.

Gear Lubricants

AMSOIL Synthetic Manual Synchromesh Transmission Fluid AMSOIL Synthe c Manual Synchromesh Transmission Fluid is a premium synthe c lubricant designed for manual transmissions and transaxles.

Common Manual-Transmission Lubricants

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It stands up to rigorous transmission pressures and resists shearing to maintain the lm strength required for excellent an -wear protec on of heavily loaded gears.

AMSOIL Manual Synchromesh Transmission Fluid exhibits outstanding performance bene ts by reducing fric on, heat and wear to increase the opera ng life of the transmission. Its superior high-temperature stability resists harmful oxida on, varnish and acid buildup. Low-temperature performance improves shi mes and transmission response in frigid temperatures.

AMSOIL Synthetic Manual Transaxle Gear LubeAMSOIL Synthe c Manual Transmission and Transaxle Gear Lube (MTG) is a premium blend of the nest synthe c base oils and high-performance addi ves. It is formulated to meet the demanding requirements of GL-4 gear lubricants where towing and heavy loading increase stress on transmission gears.

This superior lubricant resists thinning from mechanical shear, providing consistent and durable protec on even in the most demanding applica ons. AMSOIL Synthe c Manual Transaxle Gear Lube is a thermally stable uid that resists heat and oxida on to inhibit acid and varnish buildup and promote maximum equipment performance. Its robust formula on is engineered to endure high horsepower and quick shi s common in large-displacement engines like those found in muscle cars.

AMSOIL Advantage

Copper Corrosion ResistanceModern manual transmissions have speci c requirements for

copper corrosion resistance to protect copper or bronze synchromesh units in the transmission assembly. An -wear and extreme-pressure addi ve combina ons must be

speci cally formulated for these cri cal components.

AMSOIL Synchromesh Transmission Fluid is compa ble with copper and bronze synchronizer materials to provide smooth shi quali es for the life of the uid.

Smooth Synchromesh OperationSynchromesh units require speci c viscosity and fric on proper es to func on properly and provide smooth and responsive shi quali es. Fluids that impede engagement due to excessive fric on produce rough shi quali es, while uids that are too slippery prolong shi engagement and cause premature wear.

AMSOIL Synchromesh Transmission Fluid is formulated with speci c fric on modi ers to support synchromesh engagement and sustain op mal opera on. Extreme-pressure addi ves are not included in the formula on.

Heat ResistanceTransmissions housed in cast-iron, such as the NV 4500, retain heat and require a lubricant capable of cooling components during heavy loading and high-torque opera on.

While some conven onal lubricants thin out from excessive heat, AMSOIL Synthe c Manual Transmission Fluid has excellent high-temperature

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resistance and maintains viscosity despite extreme heat exposure.

Because synthe c base oils keep equipment cooler than conven onal lubricants, oxida on resistance is improved.

By helping prevent oxida on, the development of sludge and varnish deposits are signi cantly reduced, providing responsive shi ing and maximized performance.

Cold Temperature PropertiesConven onal transmission lubricants tend to thicken when exposed to cold temperatures. Viscosity increases un l the uid can no longer ow, leaving transmission gears exposed to metal-on-metal contact that increases fric on and wear and damages gears.

Thick uids impart viscometric drag, causing the transmission to work harder against uid resistance. Increased resistance reduces overall transmission e ciency and causes the engine to consume more fuel. A uid that resists thickening during cold temperatures maximizes fuel economy and enhances equipment opera on.

Synthe c base oils have excellent cold-temperature proper es; AMSOIL synthe c manual transmission uids maintain uidity below -40°F (-40 C) to coat components with a protec ve uid barrier, even in frigid temperatures. Cold-weather uidity provides reliable star ng, smooth gear changes and maximized fuel economy.

Fluid Life ExpectancySynthe c base oil structures are chemically more stable than conven onal oils. Coupled with robust addi ve packages, AMSOIL synthe c base oils provide excep onally long life for AMSOIL lubricants.

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Section Review1. What is the func on of the clutch in a manual transmission?

__________________________________________________________

__________________________________________________________

2. What is the func on of the synchromesh unit in a manual transmission?__________________________________________________________

__________________________________________________________

3. How does the synchromesh unit depend on proper lubrica on and fric onal proper es? __________________________________________________________

__________________________________________________________

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Mobile Drivetrain Fluids: Automatic Transmissions and Transaxles

Mobile Drivetrain Fluids: Section 4Automatic TransmissionsIntroduction

Sec on 4 begins with an introduc on to the components and opera on of the automa c transmission. Components that rely on automa c transmission uid (ATF) for proper opera on are discussed, with an emphasis on uid requirements and addi ve considera ons. Prior uid speci ca ons and their evolu on are also explored, including major driving forces behind speci ca on changes.

Major components, including the torque converter, clutches and clutch packs, the planetary gear system and the valve body are included; fundamental opera on and lubrica on requirements are described for each. This sec on concludes with a basic examina on of new transmission systems that are coming to market and their projected lubrica on requirements.

Section Objectives


1. Basic func on of automa c transmissions 2. How the automa c transmission is dis nguished from the manual

transmission3. Fundamental components of automa c transmissions4. Purpose of OEM uid speci ca ons 5. Basis for ghter uid speci ca ons6. How transmission uid proper es enhance transmission component

performance

Section Keywords


Clutch GlazingSlippageShudderTorque ConverterTorque Converter Lockup Clutch

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Introduction to Automatic Transmissions

Modern automa c transmissions are designed for high horsepower and torque outputs while providing an enjoyable driving experience characterized by smooth and responsive shi quali es. They di er from manual transmissions in their ability to change gear ra os automa cally without driver interac on. They also can accomplish gear changes without a loss of power to the wheels. Automa c transmissions have evolved signi cantly, with recent focus on improving overall performance and fuel economy.

Automa c transmissions use a complicated system of machinery that includes planetary gears, clutches, torque converter, valve body, elastomeric seals and gaskets. Each component relies on transmission uid for op mal opera on.

Closer inspec on of automa c transmissions reveals addi onal planetary gear sets, including wet clutches and bands that engage the gears. A hydraulic system controls the clutches and bands, and an oil pump supplies the system with uid.

This sec on examines the cri cal components of automa c transmissions, including the lubrica on proper es required for maximized performance.

OEM Performance Specifi cations for Automatic Transmissions

OEMs de ne the lubrica on requirements for the transmission; these requirements guide factory- and service- ll uid proper es to ensure proper performance for the life of the uid.

As automa c transmissions undergo design and hardware changes, uid speci ca ons o en follow suit. For example, GM introduced the DEXRON VI uid speci ca on to coincide with the development of its six-speed transmission.

Introduction to Automatic Transmissions

OEM Performance Speci cations for Automatic Transmissions

Figure 4.1Common U.S. transmission uids and speci cation changes over the years (some elds are blank due to a lack of published information)

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O en mes, OEMs develop exclusive uid tests that simulate speci c oil performance requirements. For example, GM may have a fric on test that quali es its oil; however, it is unique to GM protocol and other manufacturers do not use it.

The fric onal requirements of the transmission materials guide uid speci ca ons. For example, some transmission designs require uid with more ‘s cky’ quali es while others require a more ‘slippery’ uid.

A brief summary of how the most common uids in use in the U.S. have evolved over the years is shown in Figure 4.1.

Fundamental Components of Automatic Transmissions

The following descrip ons of automa c transmission components demonstrate func on, opera on and major lubrica on requirements.

Torque Converter

The torque converter performs the same func on as a manual transmission’s clutch; it transfers engine rota ons to the transmission, which eventually reaches the vehicle’s wheels.

OperationA torque converter is a uid coupling used to transmit rota on between two components by harnessing the movement of uid. A simpli ed way to understand how a torque converter works is to apply the fan-to-fan analogy.

Visualize the two sides of a torque converter as two fans facing each other. The fan on the right is powered by the engine and is called the pump. The fan on the le is not powered and is free to spin; it is called the turbine and is a ached to the transmission.

The pump directs air into the turbine’s blades and causes the turbine to spin. An actual pump and turbine interact just like this, only uid is used to transfer the movement between sides. The spinning turbine transfers movement to the transmission.

Fundamental Components of the Automatic Transmission

Torque Converter

Figure 4.2The torque converter is a uid coupling used to transfer engine rotations to the transmission.

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Centrifugal force inside the spinning pump draws uid to its outer walls where it is channeled to the turbine. Fluid movement creates a vacuum e ect at the center of turbine, which draws the uid out and back into the pump through a device called the stator, where the cycle repeats.

Slippage occurs between the pump and turbine because the turbine can never spin as fast as the pump side of the torque converter. The slipping between the pump and turbine causes energy loss and fuel-e ciency de cits.

The torque converter lockup clutch is used to overcome the slippage between the pump and turbine. The clutch locks the pump and turbine together to maximize fuel economy. It is engaged only during high-speed cruising condi ons. The clutch is designed to slip during accelera on and low-speed opera on.

Lubrication Requirements An -foam agents inhibit the development of foam that can develop from the rapid and constant churning inside the torque converter. During the slipping phase, the uid in the torque converter lockup clutch is exposed to high levels of shearing force that can shear the uid out of viscosity grade. The uid must be extremely shear stable and resistant to oxida on as it tolerates high shear forces and high temperatures.

Automa c transmission uids must provide fric onal proper es that last the dura on of the uid’s service life. To suppress excessive vibra on and vehicle shudder, the uid must increase the fric on it provides as the speed of the transmission increases. This is referred to as a posi ve coe cient-of-fric on-to-speed rela onship.

If the uid is unable to control fric on, the transmission’s torque converter clutch (TCC) will rotate faster than its limits and send excessive vibra on through the drivetrain to the passenger cabin, which is experienced as vehicle shudder. Key performance areas inside the torque converter lockup clutch include smooth engagement and disengagement of fric on materials and shudder suppression, as clutch shudder can cause clutch lockup.

Clutches/Clutch Packs

Clutch packs engage various gear combina ons in the planetary gear train. They are usually ac vated by hydraulics, where uid squeezes the steel plates and clutch packs together.

Lubrication Requirements Transmission uid must be shear stable to resist hydraulic pressures. It must also have certain fric onal proper es so clutches engage properly.

When clutch opera on is compromised by clutch glazing, performance and holding capacity decline. Drivers no ce clutch slippage and decreased accelera on as the clutch’s ability to transfer torque from the engine to the transmission is diminished.

Clutch glazing occurs when transmission uid heats excessively and reacts with oxygen. The by-products of this reac on develop a varnish, or glaze, on the clutch plate surface, lling in the uneven surfaces with slippery by-products. When the clutch becomes signi cantly glazed, it no longer provides the necessary fric onal characteris cs necessary for op mum engagement or disengagement of the fric on surfaces.

Clutches/Clutch Packs

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The lockup clutch in the transmission’s torque converter can also su er from glazing. Drivers may no ce an increase in fuel consump on because engine and transmission speeds (rpm) don’t match. Another consequence of the engine and transmission not locking together is that engine rota ons can surge while traveling at a constant speed.

Because AMSOIL base oils are thermally stable and fully formulated with advanced, controlled fric on-modi er addi ves, clutch fric on materials are protected from oxida on and glazing processes over the life of the uid.

Planetary Gears

Figure 4.3Automatic transmission clutches are hydraulically controlled.

Figure 4.4Planetary gears of an automatic transmission

Planetary Gears

Automa c transmissions use planetary gears to create all available gear ra os necessary for various driving condi ons and generate the low and high gears used to vary torque output. The sun gear, the planet gear and the ring gear are the three main components used to operate the planetary gear train. Each of these gears can serve as the input or output. They can also be locked in a sta onary posi on, if needed. Di erent

Fric on plate teeth

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combina ons of input/output/sta onary gears result in di erent gear ra os.

Torque demands on the gears increase during heavy-duty opera on such as hilly driving or towing. These internal forces strain the uid’s ability to maintain a protec ve uid barrier against metal-on-metal contact.

Lubrication RequirementsThe transmission uid is responsible for cooling the gears and protec ng against wear. Under high load and stressful opera on, the uid protects against scoring, pi ng and gear seizure. Rust and corrosion inhibitors protect gear surfaces from chemical degrada on. The uid must be shear stable to resist thinning out from the high-stress opera on of the planetary gear set.

Oil Pump

The transmission oil pump is located at the front of the transmission before the torque converter and is typically covered by the oil pan. It circulates and maintains oil pressure in the transmission system.

Oil enters the pump through a lter on the bo om of the oil pan. Fluid travels by pickup tube directly to the oil pump. It is circulated to the regulator and valve body, and then to the rest of the transmission system as necessary.

Lubrication RequirementsDispersants in the uid act as solvents to ensure sludge and deposits remain at acceptable levels so they do not impede lter performance and restrict oil ow. Flow restric on in the oil pump can cause sluggish opera on or oil starva on that will cause transmission failure.

Valve Body

The valve body is the transmission’s hydraulic control center. It is composed of a maze of narrow channels that direct uid to valves, clutches and bands that ini ate gear changes.

Lubrication RequirementsThe uid must have good thermal stability to inhibit sludge and deposits that can interfere with the hydraulic system. Dispersant proper es prevent solid contaminants from agglomera ng into larger masses that block narrow passages and reduce the func onality of the transmission. Restricted or blocked passages can cause erra c shi quali es and eventual gear loss.

Oil Pump

Valve Body

Figure 4.5The valve body is the hydraulic control center of the automatic transmission.

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Seals

Transmission seals and gaskets prevent transmission uid from leaking out of the system. The

automa c transmission has two main seals, the front and rear seal. The front seal allows uid to travel between the torque converter and transmission; the rear seal prevents uid from leaking past the output sha . Other seals maintain

internal pressure and provide for proper func onality of the hydraulic system.

Transmission opera on can be signi cantly compromised if seals become bri le and dry. Seals that do not func on as designed compromise transmission opera on and can lead to failure.

Lubrication RequirementsCompa bility with elastomer seal materials is necessary to ensure proper opera on. The lubricant prevents elastomeric seal materials from drying out or becoming impaired by degrada on. Transmission uids condi on seals so they maintain strength and func onality for op mal hydraulic performance and longevity.

In addi on to uid compa bility issues, seal materials degrade from heat and chemical by-products produced during opera on. A uid that controls thermal degrada on and acid buildup ul mately helps preserve the integrity of hydraulic seals.

CVT – Constant Velocity Transmissions (Continuously Variable Transmission)

Constant velocity transmissions do not rely on gears to change gear ra os. Instead, they use a belt and pulley system to generate con nuous ra o changes that provide a more e cient and smooth transi on between speed and torque changes.

OperationThe pulley system is the most common CVT con gura on. Fric on between the CVT belt and pulley is a key element to how the CVT operates. An input pulley, rather than a gear, is used to power the belt that drives the output pulley, which transfers power to the drivesha . If the fric onal interac on between the belt and pulleys is insu cient, performance declines.

Gear ra os are achieved by the variable-diameter pulleys that change posi on rela ve to one another. CVTs can generate virtually in nite gear ra os because the pulley can move in small increments to generate small gear ra o changes. The farther apart the pulleys are from each other, the lower the gear ra o; pulleys set close together achieve higher gear ra os.

Early CVT systems were plagued by frequent belt failures, but improvements to belt materials have made the modern CVT a reliable and e cient system.

Lubrication RequirementsTransmission uid for CVTs protects against wear and scu ng while maximizing the fric onal interac on between the components. CVT uids require precise fric onal proper es to supply su cient torque transfer

Seals

CVT - Constant Velocity Transmissions (Continuously Variable Transmission)

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Figure 4.6Dual-clutch transmissionUsed with kind permission from ZF Friedrichshafen AG

DCT - Dual-Clutch Transmissions

Step-Type Automatic Transmissions

between the pulleys. The uid must provide enough lubricity to adequately lubricate and maintain a full- uid lm, but it can not be so slippery that it inhibits torque transfer.

DCT – Dual-Clutch Transmissions

The dual-clutch transmission is an intermediary between an automa c and manual transmission. It has two gearboxes and two clutches. Each gearbox is used for either the even (2, 4 and 6) or odd (1, 3, 5 and reverse) set of gears. The second clutch is used to maintain power to the wheels during gear changes. The inclusion of a second clutch provides smooth shi quali es that minimize the dura on of gear changes.

OperationCurrent dual-clutch transmissions use mul -plate clutches to transfer torque from the engine. Wet clutches are mainly used in high-torque applica ons that require greater heat dissipa on. Dry clutches are typically used in low-torque applica ons.

DCT OEMs claim fuel e ciency gains of as much as 20 percent over step-type automa c transmissions because they do not have the associated idle me during gear changes.

Lubrication RequirementsThe DCT lubricant must have precisely controlled fric onal proper es to accurately operate the dual clutches. Viscosity stability is required to provide predictable clutch performance in temperature extremes.

Step-Type Automatic Transmission

The step-type automa c transmission is most common in modern vehicles and uses planetary gears to achieve gear ra os required for di erent driving condi ons.

The gears in the planetary gear train are constantly mated. Hydraulic pressure controls brake bands and clutch packs that engage and disengage the gears as needed. The uid must have good hydraulic proper es to support op mal opera on of these components.

Oil cleanliness is important for op mal opera on. Fluid contaminated by sludge and varnish can inhibit uid movement through the valve body’s narrow passages, which will impair transmission opera on. Fluid su ering

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Figure 4.7AMSOIL Multi-Vehicle ATF displays outstanding friction control properties, with anti-shudder capabilities beyond 700 hours of continuous testing. (August 2009)

AMSOIL Advantage

Frictional Properties and Anti-Shudder PerformanceAMSOIL Mul -Vehicle ATF is fully for ed with fric on

modi ers engineered to deliver outstanding clutch-holding capacity, torque-transfer and an -shudder performance over the life of the uid.

The coe cient of fric on (how two surfaces behave rela ve to their movement against one another) is a major factor in shi quality, and uids can be formulated to exhibit ‘grabby’ or ‘slippery’ characteris cs,

determined by the fric on modi ers used in the formula on.

Di erent transmission materials require di erent fric onal proper es. If fric on modi ers break down in the uid, shi quality will become hard and erra c. AMSOIL uids resist fric on modi er breakdown by using high-quality base oils in tandem with robust fric on modi ers. Their ability to maintain precise fric on performance over the life of the uid allows clutches to operate smoothly with no harsh or erra c shi ing.

from excessive contamina on can result in sluggish opera on and uid starva on. A loss of gears can occur, including possible transmission failure.

The JASO LVFA/Anti-Shudder Durability Test

The Japanese Automo ve Standards Organiza on (JASO) requires a Low Viscosity Fric on Durability (LVFD) or An -Shudder Durability (ASD) test to qualify transmission uids for use in sensi ve Asian transmissions such as those in Toyota and Nissan applica ons.

Hou

rs U

n l

Neg

a v

e Sl

ope

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AMSOIL Advantage

The results of the JASO LVFA test determine the dura on for which transmission uids maintain the posi ve fric on-to-

speed rela onship that reduces torque converter clutch shudder.

Figure 4.7 shows AMSOIL Mul -Vehicle ATF outperformed major OEM and service brands, maintaining the fric on

performance necessary for an -shudder performance for 768 hours. The next closest OEM brand was Toyota T-IV, maintaining a posi ve fric on-to-speed rela onship for 340 hours, 428 hours less than AMSOIL Mul -Vehicle ATF.

Heat/Oxidation ResistanceAll lubricants oxidize when exposed to increasing temperature; the higher the temperature the faster the oxida on rate. Oxidized oil thickens and loses lubricity, requiring more energy and increasing overall fuel consump on. Oxidized oil will also produce harmful acids that can lead to corrosion and the forma on of sludge and varnish.

AMSOIL base oils are engineered with fully saturated synthe c molecules, which makes them naturally resistant to oxida on. Fully saturated molecules have a sealed molecular structure with few openings for other molecules, such as oxygen molecules, to a ach. The fully saturated structure of AMSOIL uids resists thickening from thermal and oxida on reac ons. In addi on to their natural oxida on resistance, AMSOIL lubricants are for ed with an oxidants that help further extend uid life.

Powerful dispersants in AMSOIL automa c transmission uids prevent sludge and varnish deposits from agglomera ng into larger, damaging par cles that clog valve body passages and can harm the transmission and cause failure.

AMSOIL automa c transmission uids have excep onal high-temperature performance and oxida on resistance, providing signi cantly increased uid life expectancy over conven onal transmission uids.

The Aluminum Beaker Oxidation Test (ABOT)

The MERCON V Aluminum Beaker Oxida on Test (ABOT) is a 300-hour oxida on test in which a gear pump circulates and shears the test uid in an aluminum beaker. Fluid temperature is maintained at 311°F (155°C), and samples are drawn and analyzed at intervals throughout the test. To evaluate the uid’s tendency to a ack metal materials, metal catalysts commonly found in transmission systems are also submerged in the test uid. Figure 4.8 shows how AMSOIL Mul -Vehicle ATF stands up to the

MERCON V viscosity-increase speci ca ons.

In order for a uid to pass the current MERCON V speci ca ons, it must not exceed a 25 percent viscosity increase following the 300 hour test. AMSOIL Mul -Vehicle ATF has an ini al 34.4 cSt viscosity. In order to pass the MERCON V speci ca on, it can’t exceed 43 cSt upon comple on of the 300-hour oxida on test.

Figure 4.8 shows that AMSOIL Mul -Vehicle ATF easily passed the MERCON V benchmark with a minimal increase of 3.2 percent. It’s nal viscosity a er the test was 35.5 cSt, well below the MERCON V 25 percent viscosity-increase limit. AMSOIL Mul -Vehicle ATF is able to maintain viscosity under extreme oxida ve condi ons.

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Figure 4.8AMSOIL displays minimal viscosity increase after the Aluminum Beaker Oxidation Test (ABOT) and meets MERCON V speci cation requirements for this test. (August 2009)

Figure 4.9AMSOIL Multi-Vehicle ATF developed virtually no sludge and varnish during the Aluminum Bea-ker Oxidation Test (left), while the competitive oil demonstrates signi cant sludge and varnish (right).

Sludge and varnish develop when oxidized by-products from the oil agglomerate. The absence of sludge and varnish forma on during the 300-hour ABOT Test, shown in Figure 4.9, demonstrate AMSOIL Mul -Vehicle ATF was able to inhibit oxida on reac ons, maintaining its ability to provide clean and e cient transmission opera on.

Visc

osity

Incr

ease

(cSt

)

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AMSOIL Advantage

Shear Stability and Wear ProtectionThe uniform molecular structure of AMSOIL synthe c automa c

transmission uids contributes to their outstanding lm strength and shear performance and allows them to maintain a protec ve uid barrier during aggressive

opera on. While poor-performing, conven onal uids rupture under the pressure, AMSOIL automa c transmission

uids are for ed with an -wear and extreme-pressure addi ves that provide a sacri cial layer of protec on. Conven onal oils do not have the advantage of a uniform molecular structure and lose viscosity under normal condi ons. Synthe cs have inherent molecular strength and provide superior protec on against shear forces.

Gear Durability Test

The Gear Durability Test determines a transmission uid’s ability to prevent planetary gear wear under condi ons of high temperature and high load. The test simulates condi ons of severe uphill driving, towing, extreme high temperatures and high torque.

It is completed in two rigorous phases on a major OEM four-speed automa c transmission. The rst phase subjects the transmission to constant running speeds in second gear under high-torque condi ons. The second phase subjects the same transmission to a constant speed while doubling the amount of torque from the rst phase.

At the conclusion of the test, the transmission is disassembled and the planetary gear set is examined. Successful uids support the transmission for the en re dura on of the test with minimal tooth pi ng and gear fracture.

Figure 4.10 shows that AMSOIL Mul -Vehicle ATF passed the Gear Durability Test with very li le pi ng and no tooth fracture. Compe ve ATF Fluids A and B did not fare as well, with major pi ng to transmission gears.

Figure 4.10AMSOIL Multi-Vehicle ATF (far right) passes the Gear Durability Test. (August 2009)

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AMSOIL Advantage

KRL Shear Stability Test

A gear lubricant’s shear stability is measured by the KRL Shear Stability Test. This mandatory test quali es gear oils under the SAE J-306 standard. In the KRL Shear Stability

Test, uid is tested at 212°F (100°C) with a tapered-roller bearing under a 5,000 lb. load, spinning at 1,475 rpm. A er 40

hours of rigorous tes ng, uid viscosity loss is measured.

Figure 4.11 shows that AMSOIL Mul -Vehicle ATF performed be er than the uids compared in this study.

Figure 4.11AMSOIL Multi-Vehicle ATF demonstrates excellent initial viscosity and viscosity retention in the Shear Stability Test. (August 2009)

Cold-Temperature PropertiesCold temperatures increase the viscosity of transmission uid, which can result in fuel economy loss. Transmission opera on can also su er, from sluggish response to reduced shi ing capacity.

AMSOIL Mul -Vehicle ATF provides outstanding cold-temperature performance and provides uidity down to -53°F (-47 C). The wax-free, uniform molecular structure of AMSOIL synthe c automa c transmission uids provides responsive shi mes and improved fuel e ciency in cold

temperatures.

AMSOIL Mul -Vehicle ATF exceeds the cold-temperature performance benchmarks with a viscosity of 1,295 cP at -4°F (-20°C) and 9,800 cP at -40°F (-40°C), signi cantly below the maximum limit for MERCON V uids, which are 1,500 cP and 13,000 cP respec vely.

AMSOIL Mul -Vehicle ATF helps eliminate viscometric drag during extreme cold temperatures, which improves mechanical e ciency, fuel economy and wear protec on.

KRL Shear Stability Test40 hrs, 100°C, 5,000 load, 1,475 rpm

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FoamingThe gears, bearings and clutches in automa c transmissions churn oil and air together during opera on, which can cause foam development.

Foam harms the opera on and longevity of transmission components because it can signi cantly reduce cri cal uid- lm barriers. Foam in transmission oil can cause erra c shi ing and starve the transmission of uid, both of which can cause transmission damage or failure.

AMSOIL ATF is formulated with an -foam addi ves designed to rapidly reduce the surface tension of foam bubbles that develop. These addi ves ensure that foam rapidly collapses, minimizing the risk of entrained air and maintaining a protec ve uid barrier between components.

Foaming Tendency Testing (ASTM D-892)

The Foaming Tendency Test (ASTM D-892) evaluates a lubrica ng uid’s tendency to foam. Air is blown through the test uid at a

speci c temperature, and the volume of foam that remains a er a 10-minute se ling period is measured. The test is conducted in a number of sequences to simulate the start-stop opera ng condi ons common for automa c transmission uids.

Figure 4.12AMSOIL Multi-Vehicle ATF exceeds the cold-temperature performance of many OEM and service brands, as well as meets the viscosity limits for major speci cations such as MERCON V, MERCON LV and DEXRON VI. (August 2009)

AMSOIL Advantage

AMSOIL ATF provides outstanding cold-temperature performance compared to major OEM transmission

uids and service brands. It resists excessive thickening at -40°F (-40°C), signi cantly be er than the uids compared in Figure 4.12. Note that Castrol ATF exceeds

the limits for all three uids.

Brook eld Viscosityat -40°C (-40°F)

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Figure 4.13AMSOIL Multi-Vehicle ATF surpasses the MERCON V speci cation for foaming tendency. (August 2009)

AMSOIL Advantage

Figure 4.13 shows AMSOIL Mul -Vehicle ATF outperforms the MERCON V benchmark for foaming tendency per the

Foaming Tendency Test.

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Section Review1. How is an automa c transmission dis nguished from a manual

transmission? ___________________________________________________

___________________________________________________

2. Who sets the speci c lubrica on requirements for transmissions? ___________________________________________________

___________________________________________________

3. What drives uid speci ca on changes? ___________________________________________________

___________________________________________________

4. What do changes to uid speci ca ons usually mean in terms of uid performance? ___________________________________________________

___________________________________________________

5. What is the fundamental reason that one transmission uid cannot be used in all transmissions? ___________________________________________________

___________________________________________________

6. Automa c transmission uid must have good______________ abili es to prevent solid contaminants from collec ng into larger, channel-clogging par cles.

7. When the fric on modi ers break down in the uid, shi ing can become _______________.

8. The saturated molecular structure of the synthe c uids acts as an _______________, suppressing oxida on and oxidized by-products.

9. List two bene ts of an automa c transmission uid with excellent cold-temperature proper es. ___________________________________________________

___________________________________________________

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Mobile Drivetrain Fluids: Heavy-Duty Trucks and Transmissions

Mobile Drivetrain Fluids: Section 5Heavy-Duty Trucks and EquipmentIntroduction

Sec on 5 provides a technical introduc on to the opera on and uid requirements of powershi , hydrosta c and heavy-duty transmissions.

Section Objectives


1. Importance of uid fric on proper es2. Fluid viscosity requirements based on temperature3. Applica on demand di erences between manual and automa c

transmissions4. Bene ts of automated shi ing5. Hydrosta c transmission applica ons and bene ts6. Powershi transmission shi ing characteris cs7. Fric on requirements for powershi transmissions

Section Keywords

The following keywords are explained in this sec on. Pay par cular a en on to their explana ons as these concepts will serve as building blocks for future lessons.

Clutch Glazing

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Manual vs. Automatic Heavy-Duty Transmissions

The choice between an automa c versus a manual heavy-duty transmission is one driven by u lity. Manual heavy-duty transmissions are typically used for long-haul applica ons where fuel e ciency at high speeds and low-torque condi ons is required. Manual heavy-duty transmissions are preferred in these applica ons because they provide improved fuel e ciency during high-speed opera on. These applica ons require uids with controlled fric onal proper es to provide wear protec on at all possible opera ng temperatures.

Automa c heavy-duty transmissions are suited for applica ons that require frequent stopping and star ng, such as eet services like school buses and public transit vehicles. They are also preferred in frequent stop-and-start applica ons where high torque during accelera on is required, like garbage trucks and u lity vehicles.

Manual Heavy-Duty Transmissions

Manual heavy-duty transmissions are found in o -road equipment such as dozers, backhoe loaders, cranes, railway and mining equipment, road graders and commercial boats. They are also used in long-haul over-the-road applica ons.

They are designed with standard manual transmission con gura ons with a shi lever and clutch. In the modern over-the-road market, the automated manual transmission is becoming increasingly popular and

provides shi ing ease and maximized fuel economy over standard manual transmissions.

In general, both standard and automated heavy-duty transmissions are mechanically similar to those found in consumer applica ons. The fundamental di erences are the torque and load capaci es and how automated versions are controlled. Automated manual transmissions have a three-

bu on control sta on to select forward, reverse and neutral gears.

Automated heavy-duty manual transmissions, such as the Eaton Fuller UltraShi ™, use electronic controls and actuators to select the most e cient gear for current driving condi ons. It also incorporates fully automated shi ing for star ng and stopping and has no clutch pedal.

Frictional Properties

The proper opera on of powershi and heavy-duty transmissions is dependent on the fric onal quali es and durability of the lubrica ng uid.

Powershi clutches rely on the fric onal proper es of the uid for smooth and dependable opera on. AMSOIL uids, like Torque-Drive® (ATD), have inherent oxida ve stability to provide extra protec on against oxida on and improved shi quality.

Friction Properties

ViscosityRequirements

Heavy-Duty Manual vs. Automatic Transmissions

Heavy-Duty Manual Transmissions

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AMSOIL CT SeriesAMSOIL Synthe c Powershi Transmission Fluid comes in SAE 50 (CTL), SAE 30 (CTJ) and SAE 10W (CTG) viscosity grades. It is speci cally engineered for use in heavy-duty powershi transmissions, wet brakes and nal drives. AMSOIL SAE 50 Synthe c Powershi Transmission Fluid can be used in heavy-duty manual transmissions. It is formulated with top-quality synthe c base stocks and carefully balanced addi ves speci c to provide extended drain intervals in heavy-duty applica ons.

AMSOIL Synthe c Powershi Transmission Fluid has fric onal characteris cs that are compa ble with metallic and non-metallic fric on materials, such as those used in synchronizer units. Its enhanced stability reduces excessive brake noise and vibra on. Durable fric on proper es help eliminate clutch slippage and provide e cient clutch opera on that reduces thermal deposits and inhibits clutch glazing.

AMSOIL Synthe c Powershi Transmission Fluid is shear stable and provides excellent wear protec on in condi ons of sustained pressure, high horsepower and high torque.

AMSOIL Advantage

• Thermal and oxida on stability improves reliability and performance

• Shear stable under high thermal and load condi ons• Durable fric on control supports fric on surfaces and

shi quality• Provides instant shi response• Func ons in extreme condi ons of heat and cold• Protects from copper corrosion and rust• Inhibits foam to reduce harmful metal-on-metal

contact

Automatic Heavy-Duty Transmissions

Fluid quality and performance is extremely important for both on- and o -highway automa c transmission applica ons. These transmissions are commonly found in transit buses, motor coaches, garbage haulers, school buses, dump trucks, u lity vehicles, tow trucks and line-haul trucks.

Automa c heavy-duty transmissions are similar to

those in consumer applica ons; however, these larger versions have more gears and larger valve bodies with demanding uid requirements.

Heavy-duty automa c transmission torque converters can achieve power densi es that simulate the rst three gears in heavy-duty manual transmissions. They require shear-stable uids with high lm strength for protec on under maximum load. These transmissions use electronic controls that sense opera ng condi ons and op mize gear selec on for improved fuel economy.

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Oxida ve stability is required to protect the system under frequent star ng and stopping condi ons under heavy load.

Torque-Drive Synthetic Automatic Transmission Fluid AMSOIL Torque-Drive® Synthe c Automa c Transmission Fluid (ATD) provides superior performance for heavy-duty automa c transmission applica ons. It is engineered to resist oxida ve degrada on and sludge and varnish buildup. Torque-Drive is naturally resistant to the harmful e ects of heat and helps to preserve fric onal proper es for durable performance.

Many heavy-duty transmission uids include viscosity index improvers to stabilize the uid’s viscosity over a wide range of temperatures. AMSOIL Torque-Drive Synthe c Automa c Transmission Fluid has inherent viscosity stability due to its synthe c structure, elimina ng the need for VI improvers that shear down in extreme condi ons.

Heavy-Duty Automatic Transmissions

AMSOIL Advantage

• Thermal and oxida on stability improves reliability and performance

• Shear stable under high thermal and load condi ons• Durable fric on control supports fric on surfaces and

shi quality• Provides instant shi response• Func ons in extreme condi ons of heat and cold

Tractor Fluids and Hydrostatic Transmissions

Hydrosta c equipment relies on hydraulic uid to create mo on and power. Applica ons commonly driven by hydraulics include those found in agricultural and commercial applica ons.

The main components of the hydrosta c transmission include a pump to pressurize hydraulic uid, a motor to control the nal mechanical power of the

machine, hoses to carry the hydraulic uid and an engine that powers the hydraulic pump.

Hydrosta c transmissions can be powered over a wide range of torque-to-speed ra os and can move heavy loads with no loss of power. Hydraulic uid is used as the power transfer medium because it provides predictable

power capabili es regardless of opera ng temperatures. Hydraulic uid also provides instant iner a, which is the ability to provide instantaneous power from a res ng state. Typical manual and automa c transmissions have to overcome some iner a from a stopped or idling posi on.

Hydrosta c transmissions convert the engine’s mechanical power into uid power. Unlike components in a manual or automa c transmission, the parts in a hydrosta c transmission are easier to maintain and replace.

Hydrosta c transmissions are common in farm and tractor equipment, forkli trucks, pavement rollers, ditchers, concrete formers and a variety of

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o -road equipment. Well-known hydrosta c applica ons include Briggs & Stra on and Kohler transmissions found in consumer-tractor equipment.

AMSOIL Synthetic Tractor Hydraulic/Transmission Oil (ATH) AMSOIL Synthe c Tractor Hydraulic/Transmission Oil (ATH) is an all-weather Universal Tractor Transmission Oil (UTTO) engineered to meet the tough demands of heavy-duty, hydraulic-powered farm and commercial equipment. Its unique and robust formula on e ec vely reduces wear, resists heat, protects against rust and extends uid and equipment service life.

AMSOIL Synthe c Tractor Hydraulic/Transmission Oil provides excellent performance in extreme temperatures. It resists thinning at high temperatures and thickening at low temperatures; ATH provides uidity down to -51°F (-46°C). AMSOIL Synthe c Tractor Hydraulic/Transmission Oil eliminates the need for seasonal oil changes and exceeds the most demanding all-weather speci ca ons for both Case New Holland 3525 and 3526 (formerly Ford New Holland FNHA-2-C-200 & 2-C-201) and John Deere J20C & J20D speci ca ons.

AMSOIL Synthe c Tractor Hydraulic/Transmission Oil is formulated with durable fric on modi ers that suppress wet-brake cha er and provide con nuous fric on stability for long-term wet-brake opera on.

Tractor Fluids and Hydrostatic Transmissions

Powershift Transmissions

Heavy-duty commercial applica ons operate in a wide range of condi ons and have a unique set of transmission uid requirements. Applica ons like dozing, ripping, side cu ng and skidding logs are a few examples where the applica on has the unique need to go from forward to reverse

instantaneously.

Powershi transmissions provide the ability to shi rapidly and frequently without a loss of drive power. The operator is able to put the equipment in forward or reverse gear with immediate response. Powershi transmissions use a number of fric on surfaces to achieve these rapid maneuvers. Modern powershi transmissions require a dedicated uid engineered

AMSOIL Advantage

• Excellent extreme-temperature performance• Stable fric on control provides smooth opera on and

inhibits brake cha er• Foam control for smooth opera on• Advanced fric on proper es for instant shi response• Oxida on resistance extends lubricant and equipment

life• Seal and hose condi oners maintain hydraulic system

components• Wear protec on under all load condi ons• All-temperature performance eliminates the need for

seasonal oil changes

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with speci c, controlled fric onal proper es not found in other products.

Powershift Transmission Fluid Powershi uids perform as a general lubricant to protect components like gears, bearings and clutches; however, powershi uids must also eliminate slippage during heavy-duty, high-torque opera on. Powershi uids must provide instantaneous fric on to clutch plates so power

transfer between fric on surfaces is maximized.

Powershi uids engineered with precise fric onal proper es help maximize the shi me between materials, allowing the equipment to operate e ciently and with control. Rapid shi s reduce clutch plate slippage and help limit fric on and heat generated between the two surfaces. Rapid shi s and e cient fric on transfer maximizes equipment produc vity.

Powershi uids with inadequate fric onal characteris cs can lead to oxida on by-products deposi ng on fric on surfaces. These deposits cause plates to lose porosity and inhibit complete clutch engagement, which generates excessive heat. The process, referred to as clutch glazing, compounds as more oxida on and by-products deposit on clutch surfaces and more heat is generated and retained. Clutch glazing ul mately leads to clutch failure.

Fluids with inadequate fric onal characteris cs cause clutch materials to slip against each other. Fric on surfaces deteriorate from excessive fric on and heat when they slip against each other. When this happens, fric on material becomes suspended in the uid and is circulated in the system, which damages component surfaces. Clutch debris can clog the small ori ces in solenoid-actuated transmissions and restrict or impede the ow of uid.

Synthetic Powershift Transmission Fluids (CTJ/CTG/CTL)AMSOIL Synthe c Powershi Transmission Fluid is designed speci cally for heavy-duty powershi transmissions that operate under high-torque condi ons. It is engineered with top-quality synthe c base stocks and addi ves that provide maximized performance during extended drain intervals.

AMSOIL Synthe c Powershi Transmission Fluid is compa ble with metallic and non-metallic fric on materials. Precise fric onal characteris cs help eliminate excessive brake noise, vibra on and clutch glazing.

Powershift Transmissions

AMSOIL Advantage

• Durable holding capacity for high-torque outputs• Thermal and oxida on stability to reduce deposits and

clutch glazing• Compa ble with a wide range of fric on materials• Advanced fric on proper es provide instant shi

response• Reduces wear in pumps, brakes and transmissions• Robust formula ons double equipment up- me

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Section Review1. What property of the oil a ects shi quality?

__________________________________________________________

__________________________________________________________

2. Give one reason why a heavy-duty automa c transmission might be chosen over a manual transmission. __________________________________________________________

__________________________________________________________

3. What type of transmission would be best-suited for long-haul, low-torque opera on? __________________________________________________________

__________________________________________________________

4. Describe why the hydrosta c transmission and uid can be advantageous over other transmission styles. __________________________________________________________

__________________________________________________________

5. What is a characteris cally unique ability of the powershi transmission?__________________________________________________________

__________________________________________________________

6. Why are fric onal proper es important to powershi transmission opera on?__________________________________________________________

__________________________________________________________

7. Describe clutch glazing and the mechanisms that cause it.__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

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Mobile Drivetrain Fluids

Military MIL-PRF-2105E Performance Specifi cations for Lubricating Oil

Appendix

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App

endi

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API Service Classifi cations for Gear Oil

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SAE J-306 Automotive Gear Lubricant Viscosity Classifi cationReprinted with permission from SAEJ306 ©2005 SAE International.

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App

endi

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JASO LVFA (Anti-Shudder Durability) Test

Hours Un l Nega ve Slope

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Aluminum Beaker Oxidation Test (ABOT)

Viscosity Increase (cSt)

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App

endi

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Gear Durability Test

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KRL Shear Stability Test

KRL

Shea

r St

abili

ty T

est

40 h

rs, 1

00°C

, 5,0

00 lo

ad, 1

,475

rpm

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endi

x


Brookfi eld Viscosity (MERCON V Limits)

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66


Brookfi eld Viscosity Comparison

Broo

k e

ld V

isco

sity

at -4

0°C

(-40

°F)

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67

App

endi

x


Foam Sequence Testing

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68


Foam Tendency Limits (MERCON V Specifi cation)

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69

App

endi

x


G-2891_A1730.indd 69 5/10/11 1:38 PM

Notes

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Notes

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G2891 5/11

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